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Venous thrombosis appears to double or triple with use of drospirenone-containing oral contraceptives

Drospirenone, found in products such as Yaz® or Yasmin®, was found in two studies to carry a 2-3 fold increased risk of venous thromboembolism relative to other alternative oral contraceptives containing levonorgestrel. These findings were derived from two recent studies published in the British Medical Journal that evaluated the risk of women taking one of these two products and their subsequent risk of developing an idiopathic thromboembolic event, such as a deep vein thrombosis (DVT or a blood clot in the leg) or pulmonary embolism (PE, or a blood clot in the lungs).1,2

Both studies evaluated women between the ages 15-44 who were taking an oral contraceptive containing either levonorgestrel or drospirenone without any major risk factors for venous thromboembolism such as trauma, recent surgery, cancer, and prolonged immobility. In addition, two previous studies published in 2009 also suggested an increased risk of DVTs/PEs in drospirenone containing products. 3,4

The most important conclusions for most women are as follows:

Both new studies only apply to idiopathic cases of VTEs. Results from these studies cannot be extrapolated to patients with identifiable risk factors and thus should not be used as a guide for management in such patients.

These results also do not directly apply to individuals who have had a prior unprovoked DVT or PE who are likely at higher risk of another blood clot.

Absolute risk for most patients is relatively small. Although, the data seem compelling enough to suggest that dropirenone-containing oral contraceptives carry an increased risk of venous thromboembolism versus other oral contraceptives, actual event rates were small for both groups. For example, the trial done in the U.S. calculated an incidence rate of 30.8 events with drospirenone vs. 12.5 with levonorgestrel per 100,000 woman years of follow-up. However, this difference in rates can be stated more simply to mean that the use of dropirenone- containing oral contraceptive would produce only 18 more DVTs or PEs per 100,000 women per year than if they had been treated with a levonorgestrel oral contraceptive.

Dropirenone oral contraceptives may not be the best choice for oral contraceptives for most patients. In light of the multitude of oral contraceptive options available in the marketplace, it would seem that products containing levonorgestrel may be preferred for most women rather than Yaz or Yasmin.